1. Field of the Invention
The present invention deals with novel emulsifiers. The compounds are esters made by the reaction of sorbitol and meadowfoam acids. The introduction of the unsaturated highly stable meadowfoam acid portion of the molecule into the compounds of the present invention results in improved emulsification efficiency, improved oxidative stability and improved liquidity of the esters.
2. Description of the Art Practices
Sorbitan esters have likewise been known for years. U.S. Pat. No. 2,322,821 describes the chemistry.
Generally, unsaturated acids like oleic are used to make emulsifiers. The problem with these materials is that the oleic moiety undergoes a process called rancidity. The rancidity process causes the double bond to oxidize and produce low molecular weight aldehydes. These aldehydes have a bad odor and mal taste at low concentrations. They also polymerize to give dark colored products. The selection of the meadowfoam moiety results in improved color and odor and a heretofore unattainable surfactant.
This invention relates to the use of a particular group of exceptionally oxidatively stable meadowfoam acids to prepare sorbitol esters. The esters are made by the reaction of a meadowfoam acid and a sorbitol to make a new series of unexpectedly oxidatively stable emulsifying sorbitan esters.
Esters are a class of compounds which find applications in many diverse segments of the chemical industry. One of the problems which is encountered using non-branched fatty acids to make sorbitol based esters is the fact that the resulting products are dark in color and possess a mal odor. It is very desirable, particularly in cosmetic applications to have products that are light in color and free of bad odors.
The specific structure of the esters of the present invention determines the functional attributes of the product, including odor, color, emulsification and liquidity. There are many possible structural variations which can impact upon the performance of esters. We have learned that the presence of a unsaturated acid side of the molecule results in improved properties.
The unique structure of the meadowfoam results in sorbitan esters with oxidative stability heretofore unattainable. The fatty distribution of the oil ranges from 20 to 22 carbons and has unsaturation in specific locations. The oil contains 97% by weight higher unsaturated alkyl groups. Typically, meadowfoam oil contains 60-65% of a twenty carbon mono-carboxy acid having one unsaturation between carbon 5 and 6. Additionally, it contains 12-20% of a twenty two carbon mono-carboxy acid having one unsaturation between either carbon 5 and 6, or carbon 13 and 14 and 15-28% of a twenty two carbon mono-carboxy acid having one unsaturation between both carbon 5 and 6, or carbon 13 and 14. The combination of the fact that there are 20 to 22 carbon atoms in the group leads to lack of volatility, the presence of unsaturation leads to liquidity and the fact that the di-unsaturated moieties are not conjugated leads to outstanding oxidative stability.
Additional aspects of the invention is the application of these materials as personal care applications were the specific properties of the compound having the unique distribution of the meadowfoam on the other result in superior liquidity, lubricity, and outstanding oxidative stability. The products which result from the oxidative breakdown of unstable products are generally aldehydes. These materials have a mal odor and in addition react with fragrances and preservatives causing formulation problems. This fact makes the products of the present invention all the more important to the formulator of personal care products.
The compounds of the current invention are specific branched esters conforming to the following structure; Sorbitan Mono Meadowfoam Esters 
Wherein;
R is derived from meadowfoam and is;
60-65% by weight xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)13xe2x80x94CH3 
12-20% by weight a mixture of
xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)15xe2x80x94CH3 
and
xe2x80x94(CH2)11xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)7xe2x80x94CH3 
and
15-28% by weight
xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)6xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)6xe2x80x94CH3;
Sorbitan Di meadowfoam Ester 
Wherein;
R is derived from meadowfoam and is;
60-65% by weight xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)13xe2x80x94CH3 
12-20% by weight a mixture of
xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)15xe2x80x94CH3 
and
xe2x80x94(CH2)11xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)7xe2x80x94CH3 
and
15-28% by weight
xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)6xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)6xe2x80x94CH3;
Sorbitan Tri-meadowfoam Ester 
Wherein;
R is derived from meadowfoam and is;
60-65% by weight xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)13xe2x80x94CH3 
12-20% by weight a mixture of
xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)15xe2x80x94CH3 
and
xe2x80x94(CH2)11xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)7xe2x80x94CH3 
and
15-28% by weight
xe2x80x94(CH2)3xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)6xe2x80x94CHxe2x95x90CHxe2x80x94(CH2)6xe2x80x94CH3;
Preferred Embodiment
The preferred embodiments of the present invention are sorbitan mono-meadowfoam esters, sorbitan di-meadowfoam esters, and sorbitan tri-meadowfoam esters.